Attachment for electric amplifiers



July 22, 1930. B. WASHINGTON ATTACHMENT FOR ELECTRIC AMPL-IFIERS FiledOct. 20, 1926 A lNvENToR 'Bowden Washington,

yTORNEY tionpresent in the audio frequency ampli-l Patented July 22,1930 UNITI-m STATE-sf PATENT `@rari-lcs :soWnEN WASHINGTON,

0E NEW vomi, N. Y.,'Ass'1eNoE or ONE-TIALE To EoEEaT s. ALLYN,`0E NEWYoan, N. Y.

i l y ATTACHMENT Eon ELECTRIC AMPLIEIERS Application filed October 20,1926. Serial No. 142,978.

will 'greatly improve the volume and tone; quality of existing talkingmachines or vphonographs. -Another object is to produce a simple devicewhich may be readily attached to an existing talking machine and willcon*4 vert said machine into a so-'called electrical phonograph.'Another object is` to provide lmeans whereby the high qualityamplificaiers 'of many 'radio receivers may be applied to reproductionfrom records to a phonograph making use of the tone arm and tone chamberof said phonograph and ofthe volume control present in many ampliers.

` Another object 1s to provide an attachment of this character by meansof which an ordinary phonograph horn may be also readily used on theloud speaker of a radio receiving set by a shift of one connector or theuse of a switch. n y

As is well known the ordinary mechanical phonograph has no means ofproviding amplification. In other words, the energy applied to theneedle by the wavering groove in the record is the maximum amount ofenmust. be well within the range'of'the fre' querfcies to beVreproduced. Thisbeing so the response ofthe diaphragm to thisfundamental frequency and to the various harmonics of this frequencywill be too high inamplitude, thus causing distortion of-themusic orvoice. If the needle operatedstructureis given aA period somewhat higherthan the highest .desirable harmonics of the'instruments usuallyrecorded, this distortion will not'be present, but the device will beeX- tremely insensitive.

If an eiiicient, well designed and faithful i electron tube amplifier beinserted between ythe pick-up device and the reproducing de vice, anineiiicient but faithful pickup de vice may'jbe used-and efficiency may;be'v sacrificed for faithfulness inl the 'reproducing b device as well.This, I believe, to bev the main reason for the extremely high qualityof reproduction from so-called electrical phonographs a y means of myinvention anyone possessing a phonograph. and a highrquality audiofrequency amplifier, either' alone or within a radio receiver, mayconvert y'said-phono graph into 'a highv grade electrical phonographwithin a few minutes and without the use of tools.

Referring to the drawing, Fig. 1 is a verticalysection of one embodimentof my in'- vention. p l

Fig. 2 shows a front view of the embodiment disclosed in Fig. 1 vwiththe cover partially broken awayF Fig. 3 is a diagrammatic view of myinvention attached to a phonograph and toan audio frequency amplifierwith its auxiliary apparatus.y l

In Figs. 1 and 2,'10 is the casin for the needle actuated pick-upmember." t has at its base the flange 1l, this flange having fourperforations such as 12 and 13.` The'cover 14 of the casing' 10 may besecured by the screws such as 15 and I16. 17 is the armature Whichispreferably constructed ofhard mavnetic material and preferably having ahig natural period.` This armature 17 is actuated by the needle 18through the lever 19:` and the link 20. The lever 19 is pivoted betweenthe two pivot screws 21 and 22 held in the hangers 23 and 24, which areprefers ablyintegral ,with thevcover 14. The coils 25 and 26 areheld bythe L-shaped pole pieces;

27 and 28. lThe outer ends "of lthese pole pieces are clamped 'beneaththe built upfper-- manent magnet structure 29 as at 30 andl. The casingl()` is secured tothe back of the casing: 32 by screws isuch as 33 and34. 'Between the two casings is inserted a soft .p

rubber disc-35 and under ithe heads of. and

around. the screws 33 and 34 are inserted soft rubber bushings -36-and37. l,

The structure of the stationary magnetic system 38 of the reproducingunit is identical with that described for the pick-up, unit,` alf`though the number of turns andlsiz'e ofiwire onthe bobbins 39 and 40 maydiffer from l thewindings of 25. and 26.- `The cover 41 bears the nipple42 which may be designed to't theend of the tone arm of the'particularmake of talking machine to which theV device -is to be applied. Thiscover 1s selcured to the casing 32 by the screws such as 43 and 44 and'contains the diaphragm 45 which is held in place by the threadedllocking ring 46. The armature 17 maybe held in place against the casing10 by the resilient blocks 47 and 48. n

In Fig. Bisshown my `combined pick-up device .and reproducer 55attached-to the tone arm 56 of the phonograph 57. 'The terminals 58 and-59 of the pick-up portion-are connected lto the in-put of the vacuumtube,A

amplifier 60 which may have the' gain or volume control 63. The out-putof this amplifier is connected to the terminals 61 and 62 of thereproducing device. The cathodeheating and anode batteries for theamplier currents are thus induced in the windings l so' areV shown lat66, 67, 68 and 69. yInoperation the armature 17 is moved to and fromthe'poles27 and 2S by the action of the needle 18 in the groove of thephonograph`v record. Substantially proportional 25'l andl 26. Thesecurrents are ledV by the fleadsA 58 and 59 to the in-put of the ampli,-VVIier 6,0V andthe greatly amplified out-put is .returned by the lead 61and 62 to the windf "ings'39 and 40 of the out-put unit.

.I prefer to provide somemeans to prevent direct-transmission ofmechanical vibration or mterference between the "1n-put andoutput'portions of the device, as if this vibration was present to anyextent an overall oscillation, .howl., or squealvmight occur.v

4For this reason I have shown 'the cushion members 35, 36 and 37. It ispreferable ythat the casings 10 and 32 and the covers 14 and 41 beformed of some light and strong material'such as, die-cast aluminum ormolded phenolic insulation.

- my device, "the pick-up and the reproducer, may be manufactured andadjusted separatemicrophonic or condenser type of pick-up device may notbe substituted.v

It will vbenoted that the two elements'of i 1,771,323 f l i Iclaimzfl 1. An attachment for a phonograph comv .prising a housing -formed oit:two parts, one

part having means for securing it to the tubular tone arm ofsaid'phonograph, a needle operated electro-magnetic current modulatormounted in the other part ofsaid housing .a current. operated soundproducer, means for connecting said current modulator to an elec--tronic amplifier and meansfor connecting.

the out-put of -said amplifierl to said current operated sound producermounted inthe first mentioned part of the housing, and non-interfering`means of connecting the parts of said housing.` 2. As an article-ofmanufacture a phonograph., attachment comprising a housing havingtwoenclosing chambers, means for acoustically shielding one from the other,a needle operated electro-magnetic'.current modulating device in onesofsaid-chambers and an electromagnetically operated sound producingdevicein the other chamber, said latter device having a diaphragm and'said chamber having an outletadjacent thereto adapted tobe attached tothe tone arm of a phonograph. i Y

3. An attachment for the tone. arm of a phonograph kcomprising a housinghaving two parts,a resilient damping means between saidA parts, anelectro-magnetic pick-up in one'partof the housing having a stylusholder, an electro-magnetic sound reproducer inthe other part of thehousing, a tubular device extending from said latter part of thehousing-and adapted to be slipped on to the tonearm of the phonograph,and means for connecting a vacuum tube amplifier between said pick-upand said sound reproducer.

4. An attachment-'for a phonograph tone arm comprising two Qcup-shapedcasing members, with their closed bottom wallsspaced ap t by dampingmeans, v.means for clamping said members together, electromagnetsmounted in said members and secured to the bottom'walls thereof, anarmature and a projecting stylus for the electromagnet in one casingmember, a cover member for holdy ing the armature and stylus 1n placeand a diaphragm and an outlet plate secured to the other casing.

5. A phonographattachment comprising two casings one of which has meansfor securing it on the tone arm of a phonograph, an electromagnet and adiaphragm mounted in said casing, an electromagnet and an armaturemounted in the other casing, a needle' stylus carried by the lattercasing, resilient damping means mounted between said casings and meansfor clamping said casings to- .gether so that they may be handled as a.lunit.

6. A phonograph construction comprising a movable tone arm,an'electro-magneticreproducer removably carried by said tone arm andmovable therewith, and including a housing, an electro-magneticvibrator' mounted in the housing, an electro-magnetic pick-upAdetachably secured' to and supported by said housing, and including acasing and electromagnetic means Within said casing, a styluscooperatively connected with the electromagnetic pick-up and means yforpreventing vibratory interference between said casing and said housing.

7. In a phonograph a movable tone arm, an electro-magnetic reproducerdetachably secured to the tone arm and movable therewith, and includinga housing, an electromagnetic unit mounted within the housing, n

an air vibrating diaphragmy interposed-between said unit and the tonearm chamber, an electro-magnetic pick-up mechanism having a casingmounted co-axially with the housing of the reproducer, means forconnecting said casing to said housing, damping means located betweensaid casing, and said housing, and a pick-up'stylus carried by saideasing.

i 8. In a phonograph a movable tone arm, an Aelectro-magnetic reproducerhaving a housing provided with a 'tubular extension secured to andmovable with. the tone arm, an electro ma netic pick-up including acasing having a flange, damping means between said flange and saidreproducer housing, and

screws for securing said flange 'to said i housing.

BOWDEN WASHINGTON

